Background. The hantavirus infection is an emerging zoonotic disease, endemic in Chile, generating the hantavirus cardiopulmonary syndrome (HCPS), characterized by cardiopulmonary dysfunction with rapidly progressive respiratory failure and high lethality. For an early clinical orientation of HCPS, due to its non- specificity in symptoms and to help the differential diagnosis, some laboratory parameter that may be useful have been studied. Aim: To identify laboratory criteria as predictive factors of HCPS in patients with suspected hantavirus infection. Methodology: Retrospective cohort study of 71 patients admitted to the Hospital Guillermo Grant Benavente Emergency. We determined discriminative capacity of laboratory's parameters at the time of admission: platelets recount, hematocrit, inmunoblasts, activated partial thromboplastin time (aPTT) and aspartate aminotransferase (AST/GOT). Results: Were found significant differences in all parameters studied between confirmed patients (22) with respect to unconfirmed (49). Hematocrit, inmunoblasts, AST/GOT and aPTT had a OR > 1 and platelets count had a OR < 1. The best combination for predict HCPS was hematocrit, platelets count and AST/GOT with 90,01% sensibility and 81,63% specificity. Conclusion: The five parameters studied are good predictors of HCS in suspicious patients and they would may be useful in low complexity hospitals for quick transfer a center with critical care units.